This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A139567 #5 Mar 14 2020 09:08:09 %S A139567 8,512,33554432,137438953472,2658455991569831745807614120560689152 %N A139567 Bisection of ultraperfect numbers A139306. %H A139567 Jinyuan Wang, <a href="/A139567/b139567.txt">Table of n, a(n) for n = 1..8</a> %F A139567 a(n) = A139306(2*n-1). - _Jinyuan Wang_, Mar 14 2020 %Y A139567 Cf. A099057, A099058, A139306, A139563, A139564, A139568. %K A139567 nonn %O A139567 1,1 %A A139567 _Omar E. Pol_, May 08 2008